1. Field of the Invention
This invention relates to equipment for refilling and packing a trench or ditch, and more particularly to equipment comprising a movable supporting frame carrying a reciprocating tamping device and a drag conveyor, and to improved tamping devices and drag conveyors.
In many types of construction work, and particularly in laying pipelines, cables, or the like, a long trench or ditch is required, and the trench must be refilled and packed after the desired material has been placed therein. The refilling and packing of such a trench has heretofore generally been done using one machine for filling and a different machine for packing, or manually, or by a combination of manual and machine operations.
Frequently, the trench to be refilled and packed is along uneven or difficultly accessible terrain, such that a filler and packer to be most useful should be capable of working on uneven terrain, and from either side of the trench.
2. Description of the Prior Art
Numerous patents have been issued for machine-carried reciprocating tamping devices for use in packing a refilled trench or the like. U.S. Pat. Nos. 2,844,006; 3,128,682; 3,327,598; 3,376,799; 3,478,656 and 3,497,017 are exemplary of such devices. The machines described therein are to varying degrees useful in compacting a refilled trench, but they do not provide for refilling the trench, such that a separate filling device, or a manual operation, is required. These prior art tamping devices usually transmit an undesirable amount of shock back to the carrying vehicle and its operator.
U.S. Pat. No. 2,902,908 describes the combination of a scraper blade and a tamping unit mounted on a movable supporting frame. However, the combination described in the above patent is intended primarily for use in road building, and is neither intended nor suited for refilling and packing a trench.
Articulated vehicles for supporting ground-working implements are described in U.S. Pat. Nos. 2,788,858; 3,040,510 and 3,704,754. No. 3,704,754 describes a tractor having steerable front wheels attached to a boom pivotable relative to the rear frame section, and in certain respects is similar to the articulated vehicle described herein.
Prior to the present invention, there was no satisfactory device available which could simultaneously fill and pack a trench, and particularly there was no such device which could operate on uneven and obstructed terrain.